/*
* copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* bitstream writer API
*/
#ifndef AVCODEC_PUT_BITS_H
#define AVCODEC_PUT_BITS_H
#include <stdint.h>
#include <stddef.h>
#include "libavutil/intreadwrite.h"
#include "libavutil/avassert.h"
typedef struct PutBitContext {
uint32_t bit_buf;
int bit_left;
uint8_t *buf, *buf_ptr, *buf_end;
int size_in_bits;
} PutBitContext;
/**
* Initialize the PutBitContext s.
*
* @param buffer the buffer where to put bits
* @param buffer_size the size in bytes of buffer
*/
static inline void init_put_bits(PutBitContext *s, uint8_t *buffer,
int buffer_size)
{
if (buffer_size < 0) {
buffer_size = 0;
buffer = NULL;
}
s->size_in_bits = 8 * buffer_size;
s->buf = buffer;
s->buf_end = s->buf + buffer_size;
s->buf_ptr = s->buf;
s->bit_left = 32;
s->bit_buf = 0;
}
/**
* Rebase the bit writer onto a reallocated buffer.
*
* @param buffer the buffer where to put bits
* @param buffer_size the size in bytes of buffer,
* must be larger than the previous size
*/
static inline void rebase_put_bits(PutBitContext *s, uint8_t *buffer,
int buffer_size)
{
av_assert0(8*buffer_size > s->size_in_bits);
s->buf_end = buffer + buffer_size;
s->buf_ptr = buffer + (s->buf_ptr - s->buf);
s->buf = buffer;
s->size_in_bits = 8 * buffer_size;
}
/**
* @return the total number of bits written to the bitstream.
*/
static inline int put_bits_count(PutBitContext *s)
{
return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
}
/**
* @return the number of bits available in the bitstream.
*/
static inline int put_bits_left(PutBitContext* s)
{
return (s->buf_end - s->buf_ptr) * 8 - 32 + s->bit_left;
}
/**
* Pad the end of the output stream with zeros.
*/
static inline void flush_put_bits(PutBitContext *s)
{
#ifndef BITSTREAM_WRITER_LE
if (s->bit_left < 32)
s->bit_buf <<= s->bit_left;
#endif
while (s->bit_left < 32) {
/* XXX: should test end of buffer */
#ifdef BITSTREAM_WRITER_LE
*s->buf_ptr++ = s->bit_buf;
s->bit_buf >>= 8;
#else
*s->buf_ptr++ = s->bit_buf >> 24;
s->bit_buf <<= 8;
#endif
s->bit_left += 8;
}
s->bit_left = 32;
s->bit_buf = 0;
}
#ifdef BITSTREAM_WRITER_LE
#define avpriv_align_put_bits align_put_bits_unsupported_here
#define avpriv_put_string ff_put_string_unsupported_here
#define avpriv_copy_bits avpriv_copy_bits_unsupported_here
#else
/**
* Pad the bitstream with zeros up to the next byte boundary.
*/
void avpriv_align_put_bits(PutBitContext *s);
/**
* Put the string string in the bitstream.
*
* @param terminate_string 0-terminates the written string if value is 1
*/
void avpriv_put_string(PutBitContext *pb, const char *string,
int terminate_string);
/**
* Copy the content of src to the bitstream.
*
* @param length the number of bits of src to copy
*/
void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
#endif
/**
* Write up to 31 bits into a bitstream.
* Use put_bits32 to write 32 bits.
*/
static inline void put_bits(PutBitContext *s, int n, unsigned int value)
{
unsigned int bit_buf;
int bit_left;
av_assert2(n <= 31 && value < (1U << n));
bit_buf = s->bit_buf;
bit_left = s->bit_left;
/* XXX: optimize */
#ifdef BITSTREAM_WRITER_LE
bit_buf |= value << (32 - bit_left);
if (n >= bit_left) {
if (3 < s->buf_end - s->buf_ptr) {
AV_WL32(s->buf_ptr, bit_buf);
s->buf_ptr += 4;
} else {
av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
av_assert2(0);
}
bit_buf = value >> bit_left;
bit_left += 32;
}
bit_left -= n;
#else
if (n < bit_left) {
bit_buf = (bit_buf << n) | value;
bit_left -= n;
} else {
bit_buf <<= bit_left;
bit_buf |= value >> (n - bit_left);
if (3 < s->buf_end - s->buf_ptr) {
AV_WB32(s->buf_ptr, bit_buf);
s->buf_ptr += 4;
} else {
av_log(NULL, AV_LOG_ERROR, "Internal error, put_bits buffer too small\n");
av_assert2(0);
}
bit_left += 32 - n;
bit_buf = value;
}
#endif
s->bit_buf = bit_buf;
s->bit_left = bit_left;
}
static inline void put_sbits(PutBitContext *pb, int n, int32_t value)
{
av_assert2(n >= 0 && n <= 31);
put_bits(pb, n, av_mod_uintp2(value, n));
}
/**
* Write exactly 32 bits into a bitstream.
*/
static void av_unused put_bits32(PutBitContext *s, uint32_t value)
{
int lo = value & 0xffff;
int hi = value >> 16;
#ifdef BITSTREAM_WRITER_LE
put_bits(s, 16, lo);
put_bits(s, 16, hi);
#else
put_bits(s, 16, hi);
put_bits(s, 16, lo);
#endif
}
/**
* Return the pointer to the byte where the bitstream writer will put
* the next bit.
*/
static inline uint8_t *put_bits_ptr(PutBitContext *s)
{
return s->buf_ptr;
}
/**
* Skip the given number of bytes.
* PutBitContext must be flushed & aligned to a byte boundary before calling this.
*/
static inline void skip_put_bytes(PutBitContext *s, int n)
{
av_assert2((put_bits_count(s) & 7) == 0);
av_assert2(s->bit_left == 32);
av_assert0(n <= s->buf_end - s->buf_ptr);
s->buf_ptr += n;
}
/**
* Skip the given number of bits.
* Must only be used if the actual values in the bitstream do not matter.
* If n is 0 the behavior is undefined.
*/
static inline void skip_put_bits(PutBitContext *s, int n)
{
s->bit_left -= n;
s->buf_ptr -= 4 * (s->bit_left >> 5);
s->bit_left &= 31;
}
/**
* Change the end of the buffer.
*
* @param size the new size in bytes of the buffer where to put bits
*/
static inline void set_put_bits_buffer_size(PutBitContext *s, int size)
{
av_assert0(size <= INT_MAX/8 - 32);
s->buf_end = s->buf + size;
s->size_in_bits = 8*size;
}
#endif /* AVCODEC_PUT_BITS_H */